ORIGINAL INVESTIGATION. Continuously Increasing Number and Incidence of Fall-Induced, Fracture-Associated, spinal cord injuries in older persons

Transcription

1 ORIGINAL INVESTIGATION Continuously Increasing Number and of Fall-Induced, Fracture-Associated, Spinal Cord Injuries in Elderly Persons Pekka Kannus, MD, PhD; Seppo Niemi; Mika Palvanen, MD; Jari Parkkari, MD, PhD Background: Although osteoporosis, falls, and fractures among older adults are said to be a continuously increasing public health problem, reliable epidemiological information on their secular trends is very limited. Objective: To determine the current trend in the number and incidence of fall-induced, fracture-associated, spinal cord injuries in a typical white population (Finland, a country with about 5 million inhabitants). Methods: All Finns aged 5 years or older who were admitted to hospitals from January 1, 197, through December 31, 1995, for primary treatment of an acute fallinduced, fracture-associated, spinal cord injury were selected from the National Hospital Discharge Register. Similar patients aged 2 through 39 years served as a reference group. In each year of the study, the number and the age-specific and age-adjusted incidences of injuries were expressed as the number of patients per 1 persons. Results: The total number of fall-induced, fractureassociated, spinal cord injuries of Finnish older adults increased considerably during the study period, from 6 in 197 to 419 in 1995 (an average increase of 24% annually). The corresponding injury incidence was 5 in 197 and 27 in The age-adjusted incidence of these injuries also increased from 197 to 1995: in women, from 5 to 29, and in men, from 7 to 17 (relative increases were 48% and 143%, respectively). In the reference group, no trend changes by time were observed. Conclusions: In Finnish persons aged 5 years or older, the number of fall-induced, fracture-associated, spinal cord injuries shows a rise with a rate that cannot be explained merely by demographic changes. The finding shows an increasing influence of osteoporosis and falls on health and well-being of our older adults, and therefore, vigorous preventive measures are needed to control this development. Arch Intern Med. 2;16: From the Accident and Trauma Research Center and the Tampere Research Center of Sports Medicine, UKK Institute for Health Promotion Research, Tampere, Finland. The authors have no commercial, proprietary, or financial interest in the products or companies described in this article. FALLS AND fall-induced injuries of older adults are a major public health problem in modern societies with aging populations Because the number of older persons in these populations continues to increase, the number of falls and injuries is likely to increase as well. 4,6,7,11 Approximately 3% of the older persons living in the community and more than 5% of those living in geriatric long-stay facilities fall every year, and about 5% of those who fall do so repeatedly. 2,4 Not all falls of older adults result in injury, but 4% to 5% of the falls cause a fracture, and an additional 5% to 11% of falls cause other serious injuries, eg, serious soft tissue contusions, joint distortions and dislocations, severe wounds and lacerations, and head injuries. 2,4-6 Of the injury categories noted earlier, a fall-induced vertebral fracture is one of the most severe conditions, especially when the fracture is accompanied by an acute spinal cord injury. Despite this, very little epidemiological information on fallinduced vertebral fractures and fractureassociated spinal cord injuries in older persons is available, especially concerning their secular trends In fact, to our knowledge, no nationwide study investigating the number, incidence, and secular trends of these injuries has been published. Therefore, we determined trends in the absolute number and incidence of fall-induced, fracture-associated, spinal cord injuries, and the age-specific and age-adjusted incidence rates of these injuries in the 5-year-old and older population in Finland between 197 (4.6 million inhabitants) and 1995 (5.1 million inhabitants). We also studied the same figures in a younger reference group (patients aged 2-39 years) to determine whether the possible epidemiological changes in the study group were specific for the older population or just more general time trends in all adult age groups. Our hypothesis was that the number of fall-induced, fractureassociated, spinal cord injuries among older persons is rising at a rate that cannot be explained merely by demographic changes. 2145

2 SUBJECTS AND METHODS DATABASE FOR THE FALL-INDUCED, FRACTURE-ASSOCIATED, SPINAL CORD INJURIES This epidemiological study defined a fall-induced, fractureassociated, spinal cord injury of an older adult to be an injury that occurred in a person aged 5 years or older as a consequence of a fall from a 1-m or less standing height that resulted in hospitalization of the victim. Similar criteria have been used in previous epidemiological studies of injuries of elderly people. 3,11,16,17 Thus, all patients aged 5 years or older, and for a younger reference group all patients aged between 2 and 39 years, who were admitted to hospitals in Finland for primary treatment of an acute fall-induced, fractureassociated, spinal cord injury between January 1, 197, through December 31, 1995, were selected from the National Hospital Discharge Register (NHDR). The date of the injury and the unique personal identification number system of the Finnish citizens allowed the study to focus the analysis on each patient s first recorded hospital admission. Injuries caused by a vehicular accident or other high-energy trauma were excluded. The Finnish NHDR contains data on age, sex, place of residence, hospital number and department, place and cause of injury, diagnosis, day of admission and discharge, and place of further treatment. This statutory register has been operating since 1967 and is updated and quality-controlled by the Department of Registers and Statistics, National Research and Development Center for Welfare and Health, Helsinki, Finland. The Finnish NHDR is the oldest nationwide discharge register in the world, and data provided by this register are well suited to epidemiological purposes, ie, the register has been shown to cover the acute injuries of the population adequately (annual coverage of injuries is 95%) and to record them accurately (annual accuracy of the NHDR injury diagnoses is also 95%), and these percentages are especially good in severe injuries with clear-cut diagnoses, such as fracture-associated spinal cord injuries Fall-induced,fracture-associated,spinalcordinjurieswere recorded from the NHDR by evaluating the primary and secondarydiagnoses.accordingtothedirectivesgivenbythefinnish National Board of Health, the first diagnosis describes the mainreasonforthehospitalstay. Thesecond, third, andfourth diagnoses indicate other possible diseases or injuries. The diagnoses were coded with a 5-digit code according to the eighth and ninth revision of the International Classification of Diseases that indicated the type of injury. The eighth revision of International Classification of Diseases and its codeclass 86 for fracture-associated spinal cord injury were used in , and the corresponding ninth revision in Cases with codes identifying trauma sequelae and orthopedic or neurologic after care were excluded. The injury data were drawn from the entire population of Finland, the study thus completely covering the intended study population (Finnish nation). In other words, the absolute numbers and incidences of fallinduced, fracture-associated, spinal cord injuries were not cohort-based estimates but complete population results. CALCULATION OF THE AGE-SPECIFIC AND AGE-ADJUSTED INCIDENCE OF FALL-INDUCED, FRACTURE-ASSOCIATED, SPINAL CORD INJURIES BETWEEN 197 AND 1995 AND PREDICTION FOR THE FUTURE Annual midyear population figures for each 5-year age group (5-54, 55-59,... 9 years) between 197 and 1995 were taken from The Official Statistics of Finland. 22 In this statutory, computer-based register, every Finn is registered by his or her personal identification number, and the register is quality controlled continuously and updated by Statistics Finland, the Central Statistical Office of Finland. In each age group, the injury incidence was calculated for both sexes and was expressed as the number of cases per 1 persons per year. In calculation of the age-adjusted injury incidence, age adjustment was done by direct standardization using the mean population between 197 and 1995 as the standard population. Finally, the figures of injury incidences observed in the different age groups over the study period ( ) were used to predict the age-specific incidences and the absolute number of these fall-induced, fracture-associated, spinal cord injuries in the population in 21, 22, and 23. The prediction was based on a simple linear trend continuation method using ordinary least squares as the method of regression and r 2 and standard error of the estimate as descriptors of the fitness of the regression line to the data. The prediction was performed by first calculating the incidence regression lines for both sexes and for each age group. These regression lines were then used to determine the age- and sexspecific injury incidences in women and men aged 5 years or older until 23. Then, within each age and sex group, the predicted absolute number of injuries was obtained by multiplying the aforementioned incidence by the estimate of the number of inhabitants, the latter being obtained from the Finnish Population Projections RESULTS NUMBER AND INCIDENCE OF FALL-INDUCED, FRACTURE-ASSOCIATED, SPINAL CORD INJURIES Older Adults In persons aged 5 years or older, the annual number of fall-induced, fracture-associated, spinal cord injuries increased considerably during the study period, from 6 in 197 to 419 in 1995 (Figure 1). The average increase was 24% per year. The incidence curve for injuries also showed a clearly increasing trend, although the Finnish population of persons 5 years or older increased 36% (from 1.1 to 1.5 million) during this 25-year period: the overall incidence (per 1 persons) of fall-induced, fractureassociated, spinal cord injuries in persons aged 5 years or older was 5 in 197 and 27 in 1995 (Figure 1). The mean age of the patients also increased, in women from 66 years (197) to 78 years (1995), and in men from 62 years (197) to 69 years (1995). Despite this, the age-adjusted incidence of these fall-induced, fracture-associated, spinal cord injuries also showed an in- 2146

3 45 4 Number 4 FALL-INDUCED, FRACTURE-ASSOCIATED, SPINAL CORD INJURIES IN OLDER ADULTS IN THE FUTURE Annual No. of Adults Persons Aged 5 y crease from 197 to 1995: in women, from 5 to 29, and in men, from 7 to 17 (relative increases were 48% and 143%, respectively). When comparing the epidemiological development of the older adults fall-induced, fracture-associated, spinal cord injuries with that of other age groups or with the fracture-associated spinal cord injuries induced by mechanisms other than falling, the continuously increasing importance of the former received additional evidence. For all fracture-associated spinal cord injuries in Finland (ie, all age groups and all causes for these injuries included), the proportion of the 5-year-old or older persons fallinduced, fracture-associated, spinal cord injuries showed a steady increase, from 24% in 197 to 58% in In the population aged 5 years or older, the proportion of fall-induced, fracture-associated, spinal cord injuries (of all fracture-associated spinal cord injuries in this age group) rose from 72% to 84%. Younger Adults Persons Aged 2-39 y In patients aged 2 through 39 years, the annual number and incidence of fall-induced, fracture-associated, spinal cord injuries did not show increasing trend by time: in 197, this number and incidence (per 1 persons) were 6 and 4.5, respectively, while 67 and 4.7 in 1995 respectively, (Figure 1). AGE-SPECIFIC INCIDENCE OF FALL-INDUCED, FRACTURE-ASSOCIATED, SPINAL CORD INJURIES IN OLDER ADULTS In the youngest age groups of the elderly women and men (aged 5-69 years), the incidence of fall-induced, fractureassociated, spinal cord injuries did not show clear trend changes over time, while in the older age groups, especially in those aged 8 years or older, the injury incidence clearly increased (Figure 2) Figure 1. Number and incidence (per 1 persons) of fall-induced, fracture-associated, spinal cord injuries in Finland in persons aged 5 years or older (study group) and persons aged between 2 and 39 years (reference group) between January 1, 197, and December 31, If the aforementioned increase in the age-specific injury incidence continues, the overall incidence of older persons fall-induced, fracture-associated, spinal cord injuries (per 1 Finns aged 5 years) can be calculated to be 32, 42, and 57 in 21, 22, and 23, respectively. Together with the predicted increase in the size of the population, these incidences mean that in 21 the total number of older persons with a fall-induced, fracture-associated, spinal cord injury in Finland (5 million population) will be approximately 66, and correspondingly, 9 and 12 in 22 and 23 (Figure 3). Thus, the current number of injuries may treble by 23. COMMENT In this epidemiological study we used the entire Finnish population aged 5 years or older to describe the trends over time for the absolute number and incidence of fallinduced, fracture-associated, spinal cord injuries. No such study has been published previously, to our knowledge. We found that the overall number and incidence (per 1 persons) of these injuries rose considerably from 6 and 5, respectively, in 197, to 419 and 27 in 1995 (Figure 1). In both sexes the increase in injury incidence was most pronounced in the oldest age groups, especially in persons aged 8 years and older (Figure 2). A clear strength of our study was that data were taken from the Finnish NHDR, with proven high accuracy and excellent coverage of injuries, and that the registration of injuries included the entire population of Finland; ie, absolute numbers and incidences of fallinduced, fracture-associated, spinal cord injuries were not cohort-based estimates but complete population results. With the NHDR and the unique personal identification number system of the Finns, we were able to eliminate multiple admissions caused by transfers between hospitals and hospital departments and readmissions due to complications and other treatment problems. Our results also represent practically all incidents of fallinduced, fracture-associated, spinal cord injuries in this country, because all patients with an acute, fractureassociated, spinal cord injury are admitted to a hospital department. An additional strength of the study was that our older patients had a younger reference group (persons aged 2-39 years with similar injury diagnoses) in which no increasing number and incidence of injuries were seen during 197 through 1995 (Figure 1). In other words, the behavior of the reference group over time provided rather convincing additional evidence that our NHDRbased observations on the steeply increasing number and incidence of fall-induced, fracture-associated, spinal cord injuries among older Finns were real and not caused by defects, inaccuracies, or changes in the system of injury registration. The steady increase in the proportional figures of the older adults fall-induced, fractureassociated, spinal cord injuries (compared with those of other age groups and with the fracture-associated spinal 2147

4 y 7-79 y 6-69 y 5-59 y Figure 2. Age-specific incidence (per 1 persons) of fall-induced, fracture-associated, spinal cord injuries in Finland in women (left) and men (right) aged 5 years or older between January 1, 197, and December 31, Women s r 2 and standard error of estimate values (as descriptors of fitness of a regression line to the data) were, from the youngest to the oldest age group:.39 and 1.4;.7 and 1.8;.85 and 4.7; and.83 and 1.8, respectively. In men, the corresponding values were.44 and 1.8;.69 and 2.3;.48 and 4.7; and.81 and 8., respectively. No. of Injuries Figure 3. Number of fall-induced, fracture-associated, spinal cord injuries in Finland in persons aged 5 years or older between January 1, 197, and December 31, 1995, and prediction of the number of injuries until 23, as calculated with a regression model. The number of people in this age group is estimated to increase from 1.1 million in 197 to 2.1 million in 23. cord injuries induced by mechanisms other than falling) also supported our conclusions (see Results section). A limitation of our study is that the numbers, incidences, and secular trends of the fall-induced, fractureassociated, spinal cord injuries of the older Finns cannot be directly generalized to other populations. However, the incidence of injuries will probably develop similarly in other developed countries with an aging white population. Further studies are required to show precise results for each population. In addition, our database of injuries excluded information on comorbid illnesses, medications, and lifestyles of the patients. In other words, our finding of an increasing incidence of fall-induced, fracture-associated, spinal cord injuries among older adults in Finland remained without explanatory speculations. In this context it is also good to remember that we studied a very specific group of patients with a vertebral fracture: it has been estimated that less than half the patients with a vertebral fracture seek medical help (many osteoporotic vertebral fractures are spontaneous and not symptomatic enough to result in medical consultation), that no more than 1% come to inpatient hospital attention, and that no more than 1% have accompanying spinal cord affection. 13,15,24-35 This, however, in no way devalues the observation on the drastically increasing number and age-adjusted incidence of fall-induced, fracture-associated, spinal cord injuries among older Finns: since our database is very accurate and complete, the finding is likely to be a true reflection of a rising problem of vertebral fractures in our aging population. However, as we have noted earlier, the precise reasons for the increasing age-adjusted and age-specific incidences of fall-induced, fracture-associated, spinal cord injuries in older women and men are unknown. In the fallrelated fractures of the hip and proximal humerus, fractures for which a similar secular trend has been reported, 11,36 deterioration in the age-adjusted bone quality (caused by decreased mineral density and bone strength) and an increase in the age-adjusted incidence of falls in older adults (caused by impaired balance, coordination, proprioception, reaction time, and muscle strength) have been the most commonly offered explanations. 11,37-39 In fall-induced, fracture-associated, spinal cord injuries of older adults, both of these explanations are possible. We believe that, on average, the oldest persons ( 8 years) are less healthy and functionally less capable today than in the past; thus, persons who now survive to old age are, on average, more prone to osteoporosis, falls, and injuries than were persons of the same age in the past. In other words, increased survival of ill and frail older individuals is likely to mean increased average tendency to osteoporosis, falls, and fractures. Reduced bone strength and increased propensity for falls have, in turn, been explained by such factors as increased body height, 2148

5 greater occurrence of coexisting medical problems, poorer nutrition (calcium, vitamin D), more frequent use of drugs, poorer neuromuscular function (mobility, gait, and balance), less active lifestyles, and greater consumption of tobacco and alcohol and other related substances that increase the risk of bone loss and falling. 2,4-6,11,38-41 Our observations on fall-induced, fracture-associated, spinal cord injuries among older persons are alarming. The first concern is that not only is the incidence of these injuries rising, but also the population at risk is constantly expanding and will expand more rapidly in the near future. As a result, the largest age group in Finland (the 15-year cohort born after World War II) will reach the average age of older adults with this injury between 22 and 23. Second, the increasing mean age of the patients initially seen with a fall-induced, fractureassociated, spinal cord injury is likely to present more difficulties in the treatment of these injuries (longer time for recovery, longer rehabilitation period, and an increasing number of spinal cord injuries with severe complications such as paraplegia or tetraplegia) and rising rates of general morbid conditions and death of the patients. Provided that the observed development in the agespecific injury incidences continues, the annual number of fall-induced, fracture-associated, spinal cord injuries in Finland for persons aged 5 years or older can be estimated to be about 66 and 9 in 21 and 22, respectively (Figure 3). However, as described earlier, the largest Finnish age groups will not reach the average age of the patients until 22, and thus, the number of these injuries is expected to increase especially rapidly then. For this reason, vigorous preventive measures, such as prevention and treatment of osteoporosis and diminution of the number and severity of falls of older persons, should be urgently implemented to control the increasing burden of these age-related injuries. Accepted for publication January 6, 2. This study was supported by grants 97/9/3 and 98/ 3/24 from the Medical Research Fund of Tampere University Hospital, Tampere, Finland. We thank the Finnish Ministry of Health for its cooperation in conducting this study. Corresponding author: Pekka Kannus, MD, PhD, UKK Institute, Kaupinpuistonkatu 1, FIN-335 Tampere, Finland ( klpeka@uta.fi). REFERENCES 1. Cummings SR, Kelsey JL, Nevitt MC, O Dowd KJ. Epidemiology of osteoporosis and osteoporotic fractures. Epidemiol Rev. 1985;7: Tinetti ME, Speechley M. Prevention of falls among the elderly. N Engl J Med. 1989;32: Jones G, Nguyen T, Sambrook PN, Kelly P, Gilbert C, Eisman J. Symptomatic fracture incidence in elderly men and women: the Dubbo osteoporosis epidemiologic study (DOES). Osteoporos Int. 1994;4: Rubenstein LZ, Josephson KR, Robbins AS. Falls in the nursing home. Ann Intern Med. 1994;121: van Weel C, Vermeulen H, van den Bosch W. Falls, a community care perspective. Lancet. 1995;345: Oakley A, France-Dawson M, Fullerton D, et al. Preventing falls and subsequent injury in older people. Effective Health Care. 1996;2: Melton LJ III. Epidemiology of hip fractures: implications of the exponential increase with age. Bone. 1996;18(suppl):121S-125S. 8. Lips P. Epidemiology and predictors of fractures associated with osteoporosis. Am J Med. 1997;13(suppl):3S-11S. 9. Rivara FP, Grossman DC, Cummings P. Injury prevention: first of two parts. N Engl J Med. 1997;337: Rivara FP, Grossman DC, Cummings P. Injury prevention: second of two parts. N Engl J Med. 1997;337: Kannus P, Niemi S, Parkkari J, Palvanen M, Vuori I, Järvinen M. Hip fractures in Finland between 197 and 1997 and predictions for the future. Lancet. 1999; 353: Close J, Ellis M, Hooper R, Glucksman E, Jackson S, Swift C. Prevention of falls in the elderly trial (PROFET): a randomised controlled trial. Lancet. 1999;353: Bengnér U, Johnell O, Redlund-Johnell I. Changes in incidence and prevalence of vertebral fractures during 3 years. Calcif Tissue Int. 1988;42: Hansen MA, Overgaard K, Nielsen V-AH, Jensen GF, Gotfredson A, Christiansen C. No secular increase in the prevalence of vertebral fractures due to postmenopausal osteoporosis. Osteoporos Int. 1992;2: Cooper C, Atkinson EJ, Kotowicz M, O Fallon WM, Melton LJ III. Secular trends in the incidence of postmenopausal vertebral fractures. Calcif Tissue Int. 1992; 51: Lauritzen JB, Schwarz P, Lund B, McNair P, Transpol I. Changing incidence and residual lifetime risk of common osteoporosis-related fractures. Osteoporos Int. 1993;3: Kannus P, Palvanen M, Niemi S, et al. Increasing number and incidence of fallinduced severe head injuries in older adults. Am J Epidemiol. 1999;149: Salmela R, Koistinen V. Coverage and accuracy of the Finnish hospital discharge register [in Finnish]. Hospital. 1987;49: Keskimäki I, Aro S. Accuracy of data on diagnosis, procedures and accidents in the Finnish hospital discharge register. Int J Health Sci. 1991;2: Lüthje P, Nurmi I, Kataja M, Heliövaara M, Santavirta S. of pelvic fractures in Finland in Acta Orthop Scand. 1995;66: Honkanen R. Hospitalization due to injuries in Finland in 198. Statistics and Reviews 1/199. Kuopio, Finland: University of Kuopio; Official Statistics of Finland. Structure of Population and Vital Statistics: Whole Country and Provinces, Helsinki, Finland: Statistics Finland; Official Statistics of Finland. Population Projections Helsinki, Finland: Statistics Finland; Cooper C, Atkinson EJ, O Fallon WM, Melton LJ III. of clinically diagnosed vertebral fractures: a population-based study in Rochester, Minnesota, J Bone Miner Res. 1992;7: Cooper C, Melton LJ. Vertebral fractures: how large is the silent epidemic? BMJ. 1992;34: Jacobsen SJ, Cooper C, Gottlieb MS, Goldberg J, Yahnke DP, Melton LJ III. Hospitalization with vertebral fracture among the aged: a national population-based study, Epidemiology. 1992;3: Kanis JA, McCloskey EV. Epidemiology of vertebral osteoporosis. Bone. 1992; 13(suppl):1S-1S. 28. Spector TD, McCloskey EV, Doyle DV, Kanis JA. Prevalence of vertebral fracture in women and the relationship with bone density and symptoms: The Chingford study. J Bone Miner Res. 1993;8: Riggs BL, Melton LJ III. The worldwide problem of osteoporosis: insights afforded by epidemiology. Bone. 1995;17(suppl):55S-511S. 3. Johnell O, Gullberg B, Kanis JA. The hospital burden of vertebral fracture in Europe: a study of National Register sources. Osteoporos Int. 1997;7: Cooper C. The crippling consequences of fractures and their impact on quality of life. Am J Med. 1997;13(suppl):12S-19S. 32. Wasnich RD. Epidemiology of osteoporosis in the United States of America. Osteoporos Int. 1997;7(suppl):68S-72S. 33. Matthis C, Weber U, O Neill TW, Raspe H, and the European Vertebral Osteoporosis Study Group. Health impact associated with vertebral deformities: results from the European Vertebral Osteoporosis Study (EVOS). Osteoporos Int. 1998;8: Nevitt MC, Ettinger B, Black DM, et al. The association of radiographically detected vertebral fractures with back pain and function: a prospective study. Ann Intern Med. 1998;128: Melton LJ III, Atkinson EJ, Khosla S, O-Fallon WM, Riggs BL. Secondary osteoporosis and the risk of vertebral deformities in women. Bone. 1999;24: Kannus P, Palvanen M, Niemi S, Parkkari J, Järvinen M, Vuori I. Increasing number and incidence of osteoporotic fractures of the proximal humerus in elderly people. BMJ. 1996;313: Melton LJ III. Hip fractures: a worldwide problem today and tomorrow. Bone. 1993;14(suppl):1S-8S. 38. Obrant KJ, Bengnér U, Johnell O, Nilsson BE, Sernbo I. Increasing age-adjusted risk of fragility fractures: a sign of increasing osteoporosis in successive generations? Calcif Tissue Int. 1989;44: Greenspan SL, Myers EL, Maitland LA, Resnick NM, Hayes WC. Fall severity and bone mineral density as risk factors for hip fracture in ambulatory elderly. JAMA. 1994;271: Law MR, Wald NJ, Meade TW. Strategies for prevention of osteoporosis and hip fractures. BMJ. 1991;33: Greenspan S, Myers ER, Kiel DP, Parker RA, Hayes WC, Resnick NM. Fall direction, bone mineral density, and function: risk factors for hip fracture in frail nursing home elderly. Am J Med. 1998;14: